1. Field of the Invention
The invention relates to a nuclear reactor installation housed in a steel pressure vessel, with a gas cooled small high temperature reactor. More particularly a reactor where cooling gas flows through a core of spherical fuel elements from bottom to top, with a heat utilization system placed in the flow of cooling gas. The heat utilization system is installed above the small high temperature reactor in the reactor pressure vessel and is followed in line preferably by two circulating blowers. A hot gas conduit is installed centrally through the heat utilization system and leads from a first hot gas collector chamber above the small high temperature reactor to a second hot gas collector chamber located above the heat utilization system, and a decay heat removal system is installed in the steel pressure vessel.
2. Description of the Prior Art
A nuclear reactor installation is described in West German Application DE P No. 34 35 255.4 corresponding to U.S. application Ser. No. 780,260. In this installation the decay heat removal system consists on the primary side, of several decay heat exchangers directly following the principal heat exchangers in line constituting the heat utilization system and are traversed constantly by the entire flow of the cooling gas. The decay heat exchangers are arranged below the principal heat exchanger. On the secondary side the decay heat exchangers are each connected through a decay heat removal water circulation system an external recooling heat exchanger located geodesically higher and connected with a further heat sink, preferably a cooling tower.
For installations with small high temperature reactors, which have in common that the small reactor together with a heat utilization system (steam generator, split tubular furnace, He/He heat exchanger) is installed in a steel pressure vessel, other means and processes were additionally developed for the removal of decay heat.
Thus in West German Application DE P No. 33 45 113.3 corresponding to U.S. application Ser. No. 675,641, a nuclear power plant with a small high temperature reactor is described, wherein the decay heat is removed from the primary loop through the operational steam generators. This process has the disadvantage that the primary steam generators and blowers must have a very high availability or capacity, or upon the failure of the primary steam generators and blowers, installations in the reactor core will be exposed to very high temperatures.
West German Patentschrift DE P No. 32 12 266 and West German Offenlegungsschrift DE-OS No. 311 41 892 shows to actuate an operational concrete cooling system in the case of the failure of the operational steam generators and/or blowers for the removal of decay heat, said concrete cooling safety shell surrounding the steel pressure vessel and operated by natural circulation. The heat is transferred by radiation from the steel pressure vessel installed extensively without thermal insulation to the concrete. These two nuclear reactor plants again pose high requirements in relation to the availability of the primary steam generators and blowers and in case of a failure of these components, both at the core installations designed for cold gas temperatures and in the safety shell high temperatures are experienced.